Skip to main content
SpringerLink
Log in

Equilibrium phase relations and thermodynamics of the Cr-0 system in the temperature range of 1500 °C to 1825 °C

  • Published:
Metallurgical Transactions B Aims and scope Submit manuscript

Abstract

Phase relations and thermodynamic properties of the Cr-O system were studied at temperatures from 1500 °C to 1825 °C. In addition to Cr and Cr2O2, a third crystalline phase was found to be stable in the temperature range from 1650 °C to 1705 °C. The atomic ratio of oxygen to chromium of this phase, which decomposes upon cooling to form Cr and Cr2O3, was determined as 1.33 + 0.02, in good agreement with the formula Cr3O4. Temperatures and phase assem blages for invariant equilibria of the Cr-O system were determined as follows: Cr2O3 + Cr + Cr3O4, 1650 °C ± 2 °C; Cr3O4 + Cr + liquid oxide, 1665 °C ± 2 °C; and Cr3O4 + Cr2O3 + liquid oxide, 1705 °C ± 3 °C. The composition of the liquid oxide phase at the eutectic temperature of 1665 °C was found to be close to CrO. Relations between oxygen pressure and temperature for the univariant equilibria of the Cr-O system were established by equilibrating Cr and/or Cr2O3 starting materials in H2-CO2 mixtures of known oxygen potentials at temper atures from 1500 ΔC to 1825 °C. From this information, the standard free-energy changes (ΔGΔ) for various reactions were calculated as follows: 2Cr (s) + 3/2O2 = Cr2O3 (s): ΔG ° = -1,092,442 + 237.94T Joules, 1773 to 1923 K; 3Cr (s) + 2O2 = Cr2O4 (s): ΔG ° =-1,355,198 + 264.64T Joules, 1923 to 1938 K; and Cr (s) + l/2O2 = CrO (1): ΔG ° =-334,218 + 63.81T Joules, 1938 to 2023 K.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

References

  1. Y. Granat:Metallurg, 1936, vol. 11, pp. 35–41.

    CAS  Google Scholar 

  2. G. Grube and M. Flad:Z. Elektrochem., 1939, vol. 45, pp. 835–37.

    CAS  Google Scholar 

  3. Y. Jeannin, C. Mannerskantz, and F.D. Richardson:Trans. TMS-AIME, 1963, vol. 227, pp. 300–05.

    CAS  Google Scholar 

  4. Yu.D. Tretyakov and H. Schmalzried:Ber. Bunsen-Ges. Phys. Chem., 1965, vol. 69, pp. 396–402.

    CAS  Google Scholar 

  5. L.A. Pugliese and G.R. Fitterer:Metall. Trans., 1970, vol. 1, pp. 1997–2002.

    Article  CAS  Google Scholar 

  6. F.N. Mazandarany and R.D. Pehlke:J. Electrochem. Soc., 1914, pp. 711-14.

  7. D.C. Hilty, W.D. Forgeng, and R.L. Folkman:Trans. TMS-AIME, 1955, vol. 203, pp. 253–68.

    Google Scholar 

  8. R.E. Hook and A.M. Adair:Trans. TMS-AIME, 1964, vol. 230, pp. 1278–83.

    CAS  Google Scholar 

  9. G.K. Layden:J. Am. Ceram. Soc, 1965, vol. 48, pp. 219–20.

    Article  CAS  Google Scholar 

  10. Y.I. Ol’Shanskii and V.K. Shlepov:Dokl. Akad. Nauk SSSR111, 1953, vol. 91, pp. 561–64.

    CAS  Google Scholar 

  11. R.E. Johnson and A. Muan:J. Am. Ceram. Soc, 1968, vol. 51, pp. 430–31.

    Article  CAS  Google Scholar 

  12. L.S. Darken and R.W. Gurry:J. Am. Chem. Soc, 1945, vol. 67, pp. 1398–1412.

    Article  CAS  Google Scholar 

  13. JANAF Thermochemical Tables, NSRDS-NBS 37, 1971.

  14. A. Muan:Trans. AIME, 1955, vol. 203, pp. 965–76.

    Google Scholar 

  15. A. Muan, N.Y. Toker, and E.B. Pretorius: Pennsylvania State University, University Park, PA; Allegheny Ludlum Steel, Brackenridge, PA; unpublished research.

  16. R. Hultgren, R. Orr, P. Anderson, and K. Kelley:Selected Values of Thermodynamic Properties of Metals and Alloys, John Wiley &; Sons, New York, NY, 1963.

    Google Scholar 

  17. N.Y. Toker, L.S. Darken, and A. Muan: Allegheny Ludlum Steel, Brackenridge, PA; Pennsylvania State University, University Park, PA, unpublished research.

  18. L.S. Darken and R.W. Gurry:Physical Chemistry of Metals, McGraw-Hill, New York, NY, 1953.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Allegheny Ludlum Steel, Division of Allegheny Ludlum Corporation, 15014, Brackenridge, PA

    N. Y. Toker

  2. Departments of Geochemistry and Materials Science, The Pennyslvania State University, University Park, 16802, PA

    L. S. Darken & Arnulf Muan (Professor)

Authors
  1. N. Y. Toker
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. L. S. Darken
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Arnulf Muan
    View author publications

    You can also search for this author in PubMed Google Scholar

Additional information

Formerly Graduate Research Assistant, The Pennsylvania State University

Formerly Professor

Rights and permissions

Reprints and permissions

About this article

Cite this article

Toker, N.Y., Darken, L.S. & Muan, A. Equilibrium phase relations and thermodynamics of the Cr-0 system in the temperature range of 1500 °C to 1825 °C. Metall Trans B 22, 225–232 (1991). https://doi.org/10.1007/BF02652487

Download citation

  • Received:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF02652487

Keywords

Search

Navigation